Humans when under observation are victim to the 'Hawthorne effect'. This is when people change their behaviour when the know they are being watched. The first segment of the video is of a family recording the language change of their child however the adults would likely behave differently knowing they are also being observed leading to a lack of realism and a possible unreliability.
Chomsky argues that we are all born with an innate knowledge of the English language. This informs us that we all have the capabilities to learn how to speak and that these capabilities are activated when we grow and begin to learn. The fact that other animals cant speak in the same technical way as humans supports Chomsky's theory because it implies that they don't have the innate knowledge to allow them to speak. The video used evidence from X-ray scans to show how dogs don't have the vocal chords and passageways to vocalise in as many different ways as humans can therefore restricting their communication.
To speak humans use several different parts of their bran which all work in unison. Without all of these parts active communication wouldn't be possible in the same way. This supports Piaget's cognitive theory which states that are brain takes time to develop and it is only when the cognitive part of our brain is fully ready that we gain the capabilities to reach our limit. Without all of the areas in the cognitive section active we cannot reach that limit.
It has been found through case studies that after a certain point in the development process children and adults find it far harder to learn a language. This can be seen in the case of Genie,who was over the course of thirteen years locked away in the dark, unable to learn in any way or form. She once released tried to learn the English language but wasn't capable of fully unlocking it. This supports Vygostsky who stated that children require a certain level of social interaction for language development. Genie, having been restricted from such interaction, suffered as a consequence and was unable to learn all that was to learn.
